RA 00015.pdf - OAR@ICRISAT

Table 11. Comparison of MKJ (micro-Kjeldahl)
and TAA (Technicon Auto Analyzer)
values of protein in sorghum grain.
Average protein
Protein class Samples M K J T A A Error
(%) (no) (%) (%) (%)
7.0-7.9 6 7.65 7.55 - 1 . 3
8.0-8.9 10 8.36 8.36 0.0
9.0-9.9 9 9.53 9.49 - 0 . 4
10.0-10.9 10 10.44 10.52 +0.8
1050
900
750
600
450
300
Total number of
samples: 6 758
Range 1.84 - 5.57
Mean: 3.01
11.0-11.9 7 11.56 11.59 +0.3
12.0-12.9 10 12.35 12.41 + 0.5
13.0-13.9 11 13.31 13.34 + 0.2
14.0-14.9 13 14.44 14.49 +0.4
15.0-15.9 7 15.36 15.59 + 1.5
16.0-16.9 10 16.44 16.38 - 0 . 4
17.0-17.9 4 17.28 17.20 - 0 . 5
18.0-18.9 2 18.05 18.35 + 1.7
19.0-19.5 2 19.05 19.15 +0.5
150
2.0 2.4 2.8 3.2 3.6 4.0 4.4 4.8
U I R / P Ratio
Figure 12. Range of estimated lysine content in
6 758 sorghum samples analyzed at
ICRISAT.
between 2.07 and 4.57. A close correlation
(r = +0.93) was obtained between UIR/P and
lysine concentration (g/100 g protein) and a
regression equation calculated. Further work is
under way to determine whether this can be used
with confidence as a reliable method for prediction
of lysine values.
A range of 100 germplasm samples of eight
types (with luster, with subcoat, completely
corneous, almost corneous, intermediate, almost
floury, completely floury, and with waxy endosperm)
were analyzed in subgroups, taking
into account color-white through yellow to
brown, red to purple. The 100-seed weight
(corrected for moisture) ranged from 1.16 to 4.64
g, protein from 9.3 to 16.9 percent, starch from
72.8 to 83.6 percent, soluble sugars from 0.8 to
1.8 percent, fat from 2.2 to 5.5 percent, fiber from
1.0 to 2.3 percent, and ash from 1.2 to 2.2
percent.
Routine screening of 6 758 sorghum samples
for protein and basic amino acids using the T A A
and the DBC methods respectively gave a range
of6.0 to 21.1 percent (mean 12.1 %) protein. The
UIR/P ratio was 1.84 to 5.57 (mean 3.01) (see
Fig 12).
M i c r o b i o l o g y
Efforts are concentrated on developing an assay
method for screening large numbers of fieldgrown
plants for nitrogenase activity of bacteria
associated with their roots. The assay is based on
the reduction of acetylene to ethylene by the
nitrogenase enzyme. With as little soil disturbance
as possible, soil cores containing plant
roots are taken in metal cylinders (15-cm diameter,
22-cm length) and incubated in sealed 6-liter
plastic vessels under an atmosphere of ca. 15
percent acetylene in air. Gas samples are taken 17
and 24 hours later for gas chromatographic
analysis of ethylene production.
Cores in an atmosphere without added acetylene
produce little ethylene. It is assumed that
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